The Up Island Regional School District budget for fiscal 2009 is slated to increase 1.9 per cent.

Still, enrollment swings and a new allocation system for building costs will have a large financial impact on two of the three Up-Island district towns if the budget is approved at town meetings.

The average cost per pupil under the proposed budget is $24,137, up from $21,143 last year, a 14 per cent increase. Enrollment dropped to 325 students from 357 a year ago, a decline of nine per cent.

Chilmark faces assessment increases of $353,127, up almost 27 per cent from last year. Aquinnah’s assessment drops by $96,489, or nearly 15 per cent. West Tisbury’s assessment is almost flat, up $40,000 to $5,553,733.

Chilmark’s education cost increases are related to an increase in students to 57 from 48 students and from a new 2009 budget formula for building costs.

Under the 2009 formula, a town that builds a school, Chilmark in this case, must pay 80 per cent of the cost rather than 65 to 70 per cent in prior years, said Amy Tierney, business administrator for Martha’s Vineyard schools.

Aquinnah’s district enrollment declined to 21 students from 25 in 2008. West Tisbury enrollment was unchanged at 219 students.

The total proposed budget for the school district is $8.351 million, up $155,000 from $8.196 million last year. By town, West Tisbury is assessed at more than $5.9 million, Chilmark’s share is more than $1.8 million and Aquinnah’s portion is $599,000.

They are assessed costs proportionately, based on student enrollment at the West Tisbury and Chilmark schools, on a share of school building costs and debt, and for tuition costs for 60 children who attend the Charter School or other schools out of district.

Mrs. Tierney prepared the budget, which was approved by the district school committee on Jan. 22. School district officials will meet with all three towns to review the budget plan, beginning last night in Chilmark, Mrs. Tierney said.