database designing for paying monthly salary

[aminihojat]

I'm designing a monthly salary database in ms access and VBA that has the
following tables:
1- personal table:
fields:id,name,family,disabled(0=not disabled,1=50% disabled, 2=100%
disabled),insurancetype(1=7%,2=9%)
2- monetary table:
fields:id,salary,overtimehour,lunchmoney,tax
3-debt table:
fields:id,remainder,payment
4-year table:
field:year
5-month table:
field:month
how can I create a year that each of twelve months have 30 days since a year
has 360 days?

comments:
1-the tax list is so:
if sum of salary,overtime and lunchmoneny <= 1350000 then tax rate=0%
if sum of salary,overtime and lunchmoneny > 1350000 then tax rate=10%
if value of disabled is equal to 0 then tax is calculated as above
if value of disabled is equal to 1 then tax is calculated as above
multiplied by 50%
if value of disabled is equal to 2 then tax is 0 for that record
2-insurance:
if value of insurancetype is 1 the insurance is calculated
sosalary+overtimehour)*7%
if value of insurancetype is 2 the insurance is calculated sosalary)*9%
3-overtimehour:
the formula for overtime is so: overtime=(salary/160)*overtimehour
4-lunchmoney:
the value of this field for each month is fix. For example a person gets
200000 and another person doesn't get anything.
5-remainder,payment:
for example if a person in month 4 borrows 500000 with monthly payment
100000 we have the following list:
month remainder payment
4 500000 100000
5 400000 100000
6 300000 100000
7 200000 100000
8 100000 100000
9 0 0
in addition if this person in month 6 borrows 200000 and monthly payment
100000 we have the following list:
month remainder
payment
4 500000
100000
5 400000
100000
6 500000(=300000+200000)
200000(=100000+100000)
7 300000
200000(=100000+100000)
8 100000
100000
9 0
if this person in month 6 settles previous loan and borrows a new loanfor
example 900000 and monthly payment 150000, we have the following list:
month remainder
payment
4 500000
100000
5 400000
100000
6 900000(=0+900000)
150000(=0+150000)
7 750000
150000
8 600000
150000
9 450000
150000
10 300000
150000
11 150000
150000
12 0

if a person borrows 600000 in month 11 with monthly payment 250000 , we have
the following list:
month remainder
payment
11 600000
250000
12 350000
250000
1(next year) 100000
250000
2 0
how can we automatically transfer values of these two fields to the next
year as above?
In month 1 of next year the value of remainder field is less than the value
of payment, then how can we replace the value of payment(250000) with the
value of remainder(100000) as below:
month remainder
payment
11 600000
250000
12 350000
250000
1(next year) 100000
100000
2 0

questions:
1-can I make a unique form that entry data to personal , monetary and debt
tables ?

2-if a person gets 200000 lunch money for 30 days but this value increases
to 250000 at 21-6-1984 how can I calculate difference 50000 for 10/30 days of
month 6 and show it separately?in month 7 and after that this value will be
250000.

3-how can I create new month? For example we have calculated salary of month
6 and we want to create month 7 that salary and lunchmoney are fix can come
to records of month 7 but overtimehour that is not fix we entry data for it.

4-how can I create new year?
5-how can I calculate some field every two months?for example if lunchmoney
is 200000 for each month and I don’t calculate it for this month I must
calculate it in the next month double for example 200000*2.

6-how can I prevent to calculate the salary of a person that to be retired
for next months?

7-how can I prevent to calculate the salary of a person for example only
this month but calculate it for next month?

Sincerely yours
amini